One example of a surface to be cleaned is a roadway surface on which accumulated some snow and/or ice (which are hereafter generically referred to in a non-limitative manner as “frozen water materials”). This is generally done using a rigid blade having a lowermost edge that is in engagement with the roadway surface. The blade is attached to a vehicle, for instance a truck or the like, travelling over the roadway. In this context, the blade is often called a “snowplow”. A snowplow blade is often relatively large so as to maximize the width of the surface cleaned by a single pass. Such concept, however, assumes that the roadway surface is perfectly smooth, flat and free of obstructions. In practice, road surfaces are not. For instance, the surface height often varies irregularly from one end of the lowermost edge of the blade to the other and the surface height varies all the time as the blade moves thereon. The lowermost edge is therefore not always fully in engagement with the roadway surface over its entire length, with the result that some frozen water materials tend to remain on the roadway surface at various locations, especially where the surface height is the lowest compared to the immediate surrounding areas. The efficiency of the cleaning is thus reduced.
Road maintenance operators must often use de-icing chemicals to melt the remaining frozen water materials so as to complete the cleaning. The amounts of de-icing chemicals are generally inversely proportional to efficiency of the cleaning. Thus, if the cleaning is inefficient, more de-icing chemicals are required. This has a direct impact on the operating costs and increases the footprint on the environment.
Still, obstructions can be present on the roadway surface and be hit by the lowermost edge of the blade. Some of these obstructions can damage the blade and/or remove a portion of the roadway surface, depending on the nature of the obstructions, when using a rigid blade.
Different approaches have been suggested over the years for mitigating the difficulties experienced with fully-rigid snowplow blades. One approach is presented for instance in Swiss Patent No. 416,708 granted 15 Jul. 1966. This patent uses a series of spring-biased movable plates on the lowermost edge of the blade. It also teaches the use of bolts capable of breaking when subjected to excess stress, such as when the plates hit an obstruction. Similar arrangements are disclosed for instance in U.S. Pat. No. 3,400,475 granted 10 Sep. 1968, in Canadian Patent No. 2,423,830 granted 10 Feb. 2004 and in U.S. Pat. No. 7,467,485 granted 23 Dec. 2008. Another approach is to use a series of plates on the lowermost edge of the blade where the plates are resiliently attached to the rest of the blade. Examples are shown in U.S. Pat. No. 520,479 granted 29 May 1894 and in U.S. Pat. No. 5,743,032 granted 28 Apr. 1998.
Although existing arrangements may have been generally considered adequate for their intended purposes, they have not been entirely satisfactory in all respects. Accordingly, there is still room for many improvements in this area of technology.